响应面法优化O3/US-混凝耦合去除皮革废水中的磷

Optimized O3/US-coagulation coupling using response surface methodology for phosphorus removal in tannery wastewater

采用O3/US-混凝法去除皮革废水中的磷.结果表明,废水中的磷90%以上是以有机磷形式存在,无法通过单一条件的混凝法去除废水中的磷,臭氧氧化可以将大部分有机磷转为无机磷,该过程在超声的强化下转化率更高.在单因素试验的基础上,以总磷的去除率为响应值,采用Box-Behnken响应曲面法考察了氢氧化钙投加量、臭氧反应时间、聚丙烯酰胺(PAM)投加量、超声波功率4个因素之间的单独及交互作用.结果表明,4个因素影响顺序为:氢氧化钙投加量>PAM投加量>超声波功率>臭氧反应时间,数学模型拟合度高(Radj^2=0.995),利用该模型预测总磷的最大去除率为95.56%,在最佳反应条件:氢氧化钙投加量为718.35 mg·L^-1,臭氧反应时间为50.87 min,超声波功率为337.74 W,PAM投加量为22.27 mg·L^-1时验证实验结果的总磷去除率为93.68%,与模型预测值偏差1.88%.

In this study, the O3/US-coagulation method was investigated to remove phosphorus from tannery wastewater. The results showed that more than 90% of phosphorus in wastewater was in the form of organophosphates, which cannot be removed by the single use of coagulation. Most organophosphates were converted into inorganic phosphates by ozone oxidation, and the conversion rate of this process was promoted by ultrasonic treatment. The Box-Behnken response surface method(RSM) was adopted to examine the removal rate of total phosphorus based on the results of one-factor tests. The individual effects and interactive interactions of the four factors including calcium hydroxide dosage, ozone oxidation time, polyacrylamide(PAM) dosage and ultrasonic power were investigated. The results showed that the influence of the four factors followed a descending order as: calcium hydroxide dosage > PAM dosage > ultrasonic power > ozone oxidation time. Furthermore, the RSM model fitted well with the experimental results(Radj^2=0.995) and the estimated maximum phosphorus removal rate was 95.56%. The optimal reaction conditions were obtained as: calcium hydroxide dosage of 718.35 mg·L^-1, ozone oxidation reaction time of 50.87 min, ultrasonic power of 337.74 W and PAM dosage of 22.27 mg·L^-1. Under the optimal conditions, 93.68% of the phosphorus was removed in the validation test, which agreed well with the predicted value at a deviation of only 1.88%.